1. Field
The present disclosure relates to a method and a system for identifying one or more spot colors in a full color multi-bit image data, and processing the identified spot colors for output on an image printing system.
2. Description of Related Art
Color printing may be performed using a highlight color printing system. In this type of printing, only two inks are used in the printing process. These inks comprise a black color and a highlight color (e.g., usually a red color, or a blue color). Electronic printing systems may be designed specifically for highlight color printing. Highlight color printing systems are generally faster and less expensive than full color printing systems because only two inks are processed, as opposed to the three or four inks, which must be processed in order to obtain full color images. One such application is a teacher's edition textbook, which includes single color main text, such as black color, and highlight color answers, printed in a highlight color, such as red color.
Spot colors are recognized or standardized colors, for example, according to an industry, proprietary, and/or organizational system. Some of the known spot color classification systems include: Pantone®, Toyo, DIC, American Newspaper Publishers Association (ANPA), and HKS.
Spot color inks are used to achieve a specific color more accurately than process mixtures of cyan-magenta-yellow-black (CMYK), to avoid the halftone pattern associated with process color printing, or to print colors outside the gamut of CMYK. A spot color ink (also called “spot ink”) provides a pre-mixed color ink that is directly printed, instead of a color that is obtained by halftoned levels of CMYK components at the time when the color is being printed. Spot color inks are common in the offset printing trade, and are becoming available for digital production color systems. Typically, spot color inks are offered in the colors of popular samples-based color systems. For example, a user may acquire a particular spot ink color by selecting the color from a suite of samples of existing spot ink colors.
Spot color inks are often selected to ensure the accuracy of a specific color. For example, the red color of Xerox® Corporation's logo is specified as Pantone® 032. Many of Xerox®'s printed collaterals and packaging are printed with offset or flexographic inks specifically formulated to achieve this unique red color (i.e., Pantone® 032).
Generally, a scan of a document having a spot color would be scanned as full color image data, and then printed on the highlight color printing system. This results in black color being written to spot color areas, which destroys the purity of the desired spot color. A customer may address and fix this problem by scanning the document having a spot color to a binary image, and manually selecting areas where the customer would want the spot color to be printed. This would ensure that no black color is written in spot color areas. Also, in a scanned file, the output most likely will not be reproduced with the exactly desired RGB values (i.e., red-green-blue coordinates in RGB color space) due to normal system limitations. So, the image quality of the print could result in being unacceptable to a customer.